JHL I worked under Joseph Sutter at Sutter’s Fort in various capacities. JHL I wrote down many of his experiences in journals, which have been published in their original German language as well as some English translations. His journals include his travels from Switzerland to the U.S. and up and down the Mississippi River between 1843-1846. JHL I also wrote about his western trek where he passed the Donner Party on his way west towards Sutter’s Fort.

Wilbur book on JHL I’s time at Sutter’s Fort also includes a section on when JHL I joined the U.S. Army during the Mexican American War to use the enlistment bonus to pay off a debt he owed to his travelling companions. His journal speaks to many of the well-known people of the period in southern California.